Corona shield for electrical assembly



March 8, 1966 M. BETHEA, JR

CORONA SHIELD FOR ELECTRICAL ASSEMBLY Filed June 1, 1964 INVENTOR. (Be/flea, A17".

' fizz/MM Af/amgvs United States Patent 3,239,600 CORONA SHIELD FOR ELECTRICAL ASSEMBLY Malcolm Bethea, Jr., P.0. Box 1407, Birmingham 1, Ala. Filed June 1, 1964, Ser. No. 371,464 4 Claims. (Cl. 174-144) This invention relates to a shield for an electrical assembly and more particularly to such a shield which shall permit the voltage applied to the electrical assembly to be increased greatly without producing corona.

An object of my invention is to provide a shield for an electrical assembly which shall present a large, curved conducting surface in close proximity to irregular or sharp edges of the electrical assembly whereby a lower stress electrical field is produced adjacent the sharp or irregular portions of the assembly.

Another object of my invention is to provide a shield for an electrical assembly of the character designated which shall embody a pair of exteriorly curved abutting members whereby the only edges on the shield are within the confines or inside the general physical and electrical envelope defined by the abutting members.

A further object of my invention is to provide a shield for an electrical assembly of the character designated which shall be simple of construction, economical of manufacture and one which includes matching sections which do not require critical dimensions for installation thereof.

A further object of my invention is to provide a shield for an electrical assembly of the character designated which shall be simple to install and one which is not subject to vibration damage due to the fact that there is no large mass of material supported by long arms or the like.

A still further object of my invention is to provide a two-piece electrical shield and integral guides for attaching the shield to a clamp, yoke plate or the like, thereby facilitating assembly thereof.

As is well known in the art to which my invention relates, the electrical field surrounding an electrical assembly, such as a clamp or the like, is determined by the shape of the conducting surfaces of the assembly and v the proximity of the surfaces to a ground or other surface electricity and thereby serves as a source of radio frequency energy. To prevent this loss of electrical energy, I provide a large, curved conducting surface in close proximity to the sharp or irregular surfaces on the electrical assembly which prevents the discharge of electrical energy.

Electrical shields embodying features of my invention are illustrated in the accompanying drawing, forming a part of this application, in which:

FIG. 1 is a side elevational view, partly broken away and in section showing my improved shield mounted on a suspension clamp;

FIG. 2 is a sectional view taken generally along the line 2-2 of FIG. 1 and drawn to a smaller scale;

FIG. 3 is a fragmental view taken generally along the line 3-3 of FIG. 1.

FIG. 4 is a vertical sectional view showing a modified form of my invention; and,

FIG. 5 is a fragmental view showing a further modified form of my invention.

Referring now to the drawing for a better understanding of my invention, and more particularly to FIGS. 1-3, I show a suspension clamp assembly which comprises a suspension clamp 10 connected to a yoke plate 11 by a clevis member 12. The suspension clamp 10 is adapted to support an electrical cable or the like in the usual manner. The yoke plate 11 is also pivotally connected to a clevis member carried by an insulator assembly in a manner well understood in the art. In view of the fact that my improved shield member may be mounted on various types of electrical assemblies, no further description of the suspension clamp assembly is deemed necessary.

Preferably, my improved electrical shield comprises a pair of generally hemispherical members 13 and 14. The hemispherical member 13 is provided with an outwardly projecting lug 16 having an opening 17 therethrough while the hemispherical member 14 is provided with an outwardly projecting lug 18 having an opening 19 therethrough. As clearly shown in FIGS. 2 and 3, the base 21 of the hemispherical member 13 is substantially the same size as the base 22 of the hemispherical member 14. Accordingly, when the hemispherical members 13 and 14 are mounted in substantially abutting relation to each other, as shown in FIGS. 2 and 3, a generally spherical shield member is provided.

The hemispherical members 13 and 14 are secured to opposite sides of the yoke plate 11 by suitable securing means, such as a bolt 23 havinga nut 24. That is, the bolt 23 passes through the openings 17 and 19 provided in the lugs 16 and 18 and passes through a suitable opening 26 provided in the yoke plate 11 whereby the hemispherical members 13 and 14 are secured rigidly to tho yoke plate in close proximity to the sharp edges of th: clevis 12.

Outwardly projecting guide members 27 are formed integrally with opposite sides of the yoke plate 11 in position to extend along opposite sides of the lugs 16 and 18, as shown in FIGS. l-3. The guides 27 thus facilitate placement of the shields on the assembly and then limit pivotal movement of the shields relative to the assembly after installation.

While I have shown the hemispherical members 13 and 14 as being mounted adjacent the sharp edges of the clevis 12, it will be apparent that these members could be mounted adjacent any other sharp or irregular surfaces provided on an electrical assembly. Also, while I have shown the shield as being in the form of a pair of hemispherical members, it will be apparent that the electrical shield could comprise any number of parts so long as the overall outer shape of the shield is smoothly and convexly curved.

From the foregoing description, the operation of my improved electrical shield will be readily understood. A suitable opening 26 is provided through the yoke plate 11 of the electrical assembly for receiving the bolt 23. The hemispherical members 13 and 14 are then positioned at opposite sides of the member having the opening 26 therethrough whereby the openings 17 and 19 are in alignment with the opening 26. Accordingly, upon insertion of the bolt 23 through the openings 19, 26 and 17 and then tightening the nut 24, the members 13 and 14 are secured rigidly to the electrical assembly. By providing relatively short lugs on the hemispherical members 13 and 14, the large mass of material is supported in close proximity to the support therefor whereby there is no danger of vibration damage. That is to say, there is no large mass of material supported by elongated arms or the like. Also, the guide members 27 aid in positioning the lugs 16 and 18 whereby the openings 19, 26 and 17 are in alignment with each other.

Referring now to FIG. 4 of the drawing, I show a modified form of my invention in which hollow shield members 13 and 14 are provided. The central portion of each shield member, 13 and 14 is recessed at one side thereof as at 28 and 29, respectively, and is provided with projecting lugs 16 and 18 which lie within the confines of the recesses 28 and 29, respectively. The lugs 16 and 18 are provided with openings 17 and 19 for receiving a retaining bolt 23 hving a nut 24 The bolt 23 passes through the opening 26 provided in the yoke plate 11 whereby the shield members 13 and 14 are secured firmly to the yoke plate as described hereinabove.

In FIG. of the drawing, I show a still further modified form of my invention in which shield members 13 and 14 are provided with lugs 16* and 18 which taper inwardly toward the yoke plate 11. The lugs are positioned at opposite sides of the yoke plate 11 and are secured thereto in a manner described hereinabove by a retaining bolt indicated generally at 23 The lugs lit and 18 are thus of a shape whereby they merger with the adjacent surface of the shield members 13 and 14 and the adjacent surface of the yoke plate 11, as shown. Also, the shield members 13 and 14 are shown as being formed of a screen-like, conducting material. While I have shown my improved shield members as being formed entirely of metal, it will be apparent that the shields may be formed of a plastic-like material covered with a conducting material.

From the foregoing, it will be seen that I have devised an improved electrical shield which may be readily installed with a minimum of effort and without the danger of the shield being damaged by vibration. Also, by providing a relatively large, curved surface adjacent the sharp or irregular surfaces of the electrical assembly, the sharp areas are in a low stress electrical field whereby substantially high voltages may be applied without corona. In other words, the voltages applied to the assembly can be greatly increased without corona. Furthermore, by positioning the only edges of the shield within the confines of the composite shield member formed, my improved shield does not have any outwardly protruding edges or the like.

While I have shown my invention in several forms, it will be obvious to those skilled in the art that it is not so limited, but is susceptible of various other changes and modifications without departing from the spirit thereof, and I desire, therefore, that only such limitations shall be placed thereupon as are specifically set forth in the appended claims.

What I claim is:

1. In a shield for an electrical assembly having a platelike portion:

(a) a pair of generally hemispherical members having relatively large exposed conducting surfaces which are convexly curved,

(b) the bases of said hemispherical members being substantially equal in size to define a generally spherical member when the bases of said hemispherical members are mounted in substantial abutting relation to each other adjacent opposite sides of the plate-like portion of the assembly, whereby the only edges thereof are within the confines of and inside the general physical and electrical envelope defined by the abutting members,

(c) a lug-like member carried by each abutting member and adapted to extend along opposite sides of said plate-like portion in alignment with each other,

(d) there being an opening through each lug-like member and through said plate-like portion, and

(e) a securing bolt passing through the openings in the aligned lug-like members and said openings in the plate-like portion securing said hemispherical members to said plate-like portion of the electrical assembly.

2. In a shield for an electrical assembly as defined in claim 1 in which the lug-like member is positioned within the confines of the composite generally spherical member.

3. In a shield for an electrical assembly as defined in claim I in which a lug-like member projects outwardly of each hemispherical member and is tapered toward the outer end thereof whereby it merges generally with an adjacent portion of said electrical assembly.

4. A shield for an electrical assembly as defined in claim 1 in which guide members are carried by said platelike portion along opposite sides of said lug-like member.

References Cited by the Examiner UNITED STATES PATENTS 1,972,616 9/1934 Austin. 1,997,627 4/ 1935 Casey. 2,865,982 12/1958 McCoy et a1 174144 X 3,046,327 7/1962 Harmon 174127 X FOREIGN PATENTS 879,234 11/1942 France.

LARAMIE E. ASKIN, Primary Examiner. 

1. IN A SHIELD FOR AN ELECTRICAL ASSEMBLY HAVING A PLATELIKE PORTION: (A) A PAIR OF GENERALLY HEMISPHERICAL MEMBERS HAVING RELATIVELY LARGE EXPOSED CONDUCTING SURFACES WHICH ARE CONVEXLY CURVED, (B) THE BASES OF SAID HEMISPHERICAL MEMBERS BEING SUBSTANTIALLY EQUAL IN SIZE TO DEFINE A GENERALLY SPHERICAL MEMBER WHEN THE BASES OF SAID HEMISPHERICAL MEMBERS ARE MOUNTED IN SUBSTANTIAL ABUTTING RELATION TO EACH OTHER ADJACENT OPPOSITE SIDES OF THE PLATE-LIKE PORTION OF THE ASSEMBLY, WHEREBY THE ONLY EDGES THEREOF ARE WITHIN THE CONFINES OF AND INSIDE THE GENERAL PHYSICAL AND ELECTRICAL ENVELOPE DEFINED BY THE ABUTTING MEMBERS, (C) A LUG-LIKE MEMBER CARRIED BY EACH ABUTTING MEMBER AND ADAPTED TO EXTEND ALONG OPPOSITE SIDES OF SAID PLATE-LIKE PORTION IN ALIGNMENT WITH EACH OTHER, (D) THERE BEING AN OPENING THROUGH EACH LUG-LIKE MEMBER AND THROUGH SAID PLATE-LIKE PORTION, AND (E) A SECURING BOLT PASSING THROUGH THE OPENINGS IN THE ALIGNED LUG-LIKE MEMBERS AND SAID OPENINGS IN THE PLATE-LIKE PORTION SECURING SAID HEMISPHERICAL MEMBERS TO SAID PLATE-LIKE PORTION OF THE ELECTRICAL ASSEMBLY. 